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Using the bgp default local-preference Command

In Figure 32, AS 873 receives updates for network 192.168.5.0/24 from AS 32 and AS 17.

Figure 32: Configuring the Local-Preference Attribute

Image g013189.gif

The following commands configure router LA:



host1(config-router)#router bgp 873 

host1(config-router)#neighbor 10.72.4.2 remote-as
32 

host1(config-router)#neighbor 10.2.2.4 remote-as
873 

host1(config-router)#bgp default local-preference
125

The following commands configure router SanJose:



host2(config-router)#router bgp 873 

host2(config-router)#neighbor 10.5.5.1 remote-as
17 

host2(config-router)#neighbor 10.2.2.3 remote-as
873 

host2(config-router)#bgp default local-preference
200

Router LA sets the local preference for all updates from AS 32 to 125. Router SanJose sets the local preference for all updates from AS 17 to 200. Because router LA and router SanJose exchange local preference information within AS 873, they both recognize that routes to network 192.168.5.0/24 in AS 293 have a higher local preference when they come to AS 873 from AS 17 than when they come from AS 32. As a result, both router LA and router SanJose prefer to reach this network through router Boston in AS 17.

bgp default local-preference

Use to change the default local preference value.
Changes apply automatically whenever BGP subsequently runs the best-path decision process for a destination prefix; that is, whenever a best route is picked for a given prefix.
To force BGP to run the decision process on routes already received, you must use the clear ip bgp command to perform an inbound soft clear or hard clear of the current BGP session.
Use the no version to restore the default value, 100.
See bgp default local-preference.

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